I recently just bought my 1st dslr (40d 28-135mm f/3.5-5.6). Now im pretty familiar with how iso, aperture, shutter speed all effect the exposure. My question has to do with the lenses. Does the "f/3.5-5.6" represent the min-max aperture you can use with that particular lens? If not what exactly do those #'s mean? Also what does it mean when someone says they need a slower or faster lens and how does that effect the pictures taking prosess? Thanks for the help!!

28-135mm f/3.5-5.6 would be on a zoom lens and f/3.5 would be the maximum aperture at the minimum focal length (28mm) and 5.6 would be the maximum aperture at the maximum focal length (135mm). A 'faster' lens usually means that it has a smaller f-stop number > larger maximum aperture > allows more light > allows a 'faster' shutter speed. Sometimes (seldom) they mean that the auto-focus is faster. - TF

So if I set my camera's aperture higher than say f/5.6 at 135mm, will it effect the picture at all, or does it not even realize you've gone beyond the specs? BTW OldClicker, your explanation was super easy to understand and it helped me out ALOT. Thanks!!

28-135mm f/3.5-5.6 would be on a zoom lens and f/3.5 would be the maximum aperture at the minimum focal length (28mm) and 5.6 would be the maximum aperture at the maximum focal length (135mm). A 'faster' lens usually means that it has a smaller f-stop number > larger maximum aperture > allows more light > allows a 'faster' shutter speed. Sometimes (seldom) they mean that the auto-focus is faster. - TF

Click to expand...

I think this is a typo.. f3.5 would be the widest aperture at 28mm, and 5.6 would be the widest aperture at 135mm. The max aperture changes as you zoom. The minimum aperture would be the same the whole way through (f22 or something like that).

Many mid-priced zooms have variable apertures like this. It makes the lens cheaper to make and lighter. More expensive (pro) lenses have constant f2.8 apertures throughout their entire zoom range, but they are more expensive and heavier since they need larger lens elements. f2.8 lets in more light, which means you can use faster shutter speeds, and are referred to as fast lenses. Also at large apertures (f2.8) you get a narrow depth of field, which works well to separate the subject from the background.

If you don't want to spend a lot on a fast zoom, take a look at prime lenses. You get even faster (f1.8, f1.4, etc) and very good image quality (better than most zooms) for a fraction of the price!

I think this is a typo.. f3.5 would be the widest aperture at 28mm, and 5.6 would be the widest aperture at 135mm. The max aperture changes as you zoom. The minimum aperture would be the same the whole way through (f22 or something like that).

Many mid-priced zooms have variable apertures like this. It makes the lens cheaper to make and lighter. More expensive (pro) lenses have constant f2.8 apertures throughout their entire zoom range, but they are more expensive and heavier since they need larger lens elements. f2.8 lets in more light, which means you can use faster shutter speeds, and are referred to as fast lenses. Also at large apertures (f2.8) you get a narrow depth of field, which works well to separate the subject from the background.

If you don't want to spend a lot on a fast zoom, take a look at prime lenses. You get even faster (f1.8, f1.4, etc) and very good image quality (better than most zooms) for a fraction of the price!

Click to expand...

You're really confusing me. Didn't you just say the same thing?

"...f/3.5 would be the maximum aperture at the minimum focal length (28mm)..."